B4.1 - Ecosystems

Question 1

What do arrows on a food chain show?

Answer 1

• the transfer of biomass

- transfer of energy

Question 2

what is the difference between a food chain and a food web?

Answer 2

a food chain is a small section of the whole food web

Question 3

what do food chains show?

Answer 3

the feeding relationship in an ecosystem

Question 4

what are producers?

Answer 4

organisms that make their own food through photosynthesis

Question 5

what are primary consumers?

Answer 5

animals that eat plants or algae (herbivores)

Question 6

what are secondary consumers?

Answer 6

carnivores that eat herbivores

Question 7

what is a tertiary consumer?

Answer 7

a carnivore that eats other carnivores

Question 8

what are apex predators?

Answer 8

carnivores that have no other predators

Question 9

what are decomposers

Answer 9

organisms that get energy from feeding on dead materials

Question 10

what are consumers?

Answer 10

organisms that cannot make their own food and so have to eat other organisms

Question 11

what are trophic levels?

Answer 11

each step in the food chain (where they feed)

Question 12

what is a community?

Answer 12

organisms living within an ecosystem

Question 13

define population

Answer 13

the total number of organisms of each species

Question 14

what happens when an organism grows?

Answer 14

increases its biomass

Question 15

state the factors affecting ecosystems and give a brief description

Answer 15

• biotic (living - beech trees, squirrels, hedgehogs)
• abiotic (nonliving - amount of rainfall, temperature of ecosystem)

Question 16

what biotic factors affect communities? (4)

Answer 16

• food availability
• breeding partners
• COMPETITION
• new pathogens

Question 17

how does light intensity affect communities?

Answer 17

• greater light available = greater plant success

- plants adapt for maximum absorption (larger leaves in low light)

Question 18

how does temperature affect communities?

Answer 18

• affects enzymes controlling metabolic reactions

- plants develop faster

Question 19

how does low moisture level affect plants?

Answer 19

• causes plants to wilt (low turgor pressure)
• water needed to keep cells turgid
• affects photosynthesis

Question 20

what does the pH of soil affect?

Answer 20

• biological activity in soil

- availability of certain minerals

Question 21

what kind of plants grow better in acidic soils?

Answer 21

ferns

Question 22

what do plants need to survive? (5)

Answer 22

• light
• water
• carbon dioxide
• minerals
• space

Question 23

what do animals need to survive? (5)

Answer 23

• food
• water
• breeding partner
• space
• shelter

Question 24

define population

Answer 24

the number of organisms of each species living in an area

Question 25

what is interdependence within a community?

Answer 25

how different organisms depend on each other

Question 26

what are ecological relationships?

Answer 26

interactions between organisms

Question 27

what are the three main types of ecological relationships

Answer 27

- predation - mutualism - parasitism

Question 28

what is predation the relationship of?

Answer 28

- relationship between predator and prey

Question 29

what is mutualistic relationship?

Answer 29

- both organisms benefit

Question 30

give an example of a mutualistic relationship

Answer 30

bees taking pollen from plants | bees can make honey, plants become fertilised

Question 31

what is a parasitism relationship?

Answer 31

one organism gains (parasite), other suffers (host)

Question 32

give an example of a parasitism relationship

Answer 32

tapeworms in a human’s digestive system

Question 33

what is commensalism?

Answer 33

one organism benefits from, but the other one is unaffected

Question 34

what is an example of a commensalistic relationship?

Answer 34

tree frogs use plants as protection

Question 35

what is a biotic factor?

Answer 35

a factor relating to animals (ie. competition of mating)

Question 36

what is an abiotic factor?

Answer 36

a factor which is not living? (ie. rainfall)

Question 37

why do food chains not exceed 4/5 tertiary levels?

Answer 37

not enough energy can be transferred to sustain life processes) - because of 10% rule

Question 38

what does a pyramid of numbers show?

Answer 38

- the population at each trophic level (how many there are)

Question 39

what do pyramid of numbers not take into account?

Answer 39

the size of the organism present

Question 40

how do scientists calculate biomass?

Answer 40

- get dead organism - dry the organism in a kiln (evaporate water mass) - then measure it CALLED DRY MASS

Question 41

how do scientists calculate the total biomass at each trophic level?

Answer 41

measure average mass of each organism and multiply by the number of organisms present

Question 42

state three reasons biomass is lost between trophic levels

Answer 42

- not all organism is eaten (animal bones/ plant roots) - biomass is used during respiration - some parts of organism cannot be digested (hair/teeth) - released as waste products (excretion/ urine)

Question 43

what is the nutrient cycle?

Answer 43

the process in which materials are passed between biotic and abiotic components of an ecosystem

Question 44

what is carbon used to make?

Answer 44

GLUCOSE which makes... - carbohydrates - fat - dna - proteins

Question 45

in what form can organisms use nitrogen?

Answer 45

when part of a compound (like a nitrate)

Question 46

why do organisms use nitrogen?

Answer 46

- DNA | - proteins

Question 47

Apart from providing water to organisms, describe another benefit of the water cycle

Answer 47

transports nutrients (helps replenish nutrients in different habitats)

Question 48

how is carbon removed from the atmosphere?

Answer 48

- photosynthesis

Question 49

how is carbon released back into the atmosphere? (3)

Answer 49

- respiration - decomposition - burning fossil fuels

Question 50

how does the level of atmospheric carbon vary throughout 24 hours?

Answer 50

- decreases during daytime (photosynthesis) | - increases during nighttime (no photosynthesis, but respiration continues)

Question 51

how do decomposers help the nutrient cycle?

Answer 51

release nutrients (can be recycled)

Question 52

what are detritivores?

Answer 52

small animals which shred organic material to small pieces (create larger surface area for decomposers)

Question 53

how do temperatures affect rate of decomposition?

Answer 53

- too high = enzymes used by microorganisms denature (they die) - too low = rate of enzyme controlled reactions too slow

Question 54

how does lack of water in environments affect rate of decomposition?

Answer 54

- not enough water = reactions slow down/stop

Question 55

how does lack of oxygen affect decomposition?

Answer 55

decreases, oxygen needed for microorganism to respire (so cannot survive)

Question 56

what is the equation to calculate the rate of decay of material?

Answer 56

rate of decay (g/day) = change in mass (g) / time (day)

Question 57

give 3 examples of detritivores

Answer 57

- earthworm - woodlouse - maggot

Question 58

what 3 factors affect rate of decomposition?

Answer 58

water level, temperature, oxygen level

Question 59

difference between role of nitrogen-fixing bacteria and nitrifying bacteria (2)

Answer 59

- nitrifying turns ammonia to nitrates - nitrogen-fixing turns nitrogen into nitrates